Some had worked on my car. When i got it back, the radiator fans won't come on, and the temp gauge isn't working. Is there a fuse or resister? ARe the two issues even connected to one another?

 

Which car?

either way they are not related. Temp gauge runs off of a one wire resistance type sensor on the drivers side head. which the cooling fan itself is either ECM controlled via a coolant temp sensor or a different resistance type sensor located on the passenger side head or both. Assuming this is the 89 start with the coolant temp sensor and check the relays and sensors in both heads and to the fan. For the 86 check the relay and the wiring to the sensor's in both heads and the wiring to the fan. the sensor in the pass side head just grounds at a certain temp to complete the circuit.